1. Field of the Invention
The subject invention generally pertains to refrigerant systems with multiple compressors and more specifically to preventing liquid refrigerant from migrating to an inactive compressor.
2. Description of Related Art
When using a refrigerant system for process or for cooling a room or some other comfort zone of a building, often the system includes a single evaporator/condenser circuit with two or more compressors. Usually all of the compressors run when the cooling demand is high; however, as the cooling demand decreases, some of the compressors can be turned off. Unfortunately, running one compressor while leaving another of the same refrigerant circuit inactive can create problems.
In particular, refrigerant tends to condense near the inactive compressor, because the inactive compressor is relatively cool. As the refrigerant condenses in the vicinity of the inactive compressor, more refrigerant migrates to the area. Eventually, the inactive suction or discharge line leading to the compressor and/or the compressor itself can become flooded with liquid refrigerant. Later, when the compressor restarts, the liquid refrigerant may damage the compressor.
For example, starting a compressor with liquid refrigerant in its suction line can create destructively high forces within the compressor as the compressor tries compressing the virtually incompressible liquid. If the discharge line of the compressor is flooded, the compressor""s discharge valve may be damaged, as such valves are typically designed for gas flow: not liquid. If the compressor itself becomes flooded, the liquid refrigerant may wash the oil from the compressor""s bearings, or create the same problems as those of a flooded suction or discharge line.
One way to prevent refrigerant from condensing within a compressor is to electrically heat the compressor. Such an approach, however, not only consumes electrical energy, but also does little in preventing liquid refrigerant from accumulating in the suction or discharge lines. Moreover, if an electrical heater were to fail due to a relay failure, blown fuse, a break in the electrical line, or some other cause, a flooded compressor might still be started and perhaps damaged.
Consequently, a need exists for a reliable, cost-effective approach for inhibiting liquid refrigerant from flooding an inactive compressor and its adjacent suction or discharge lines.
To avoid flooding an inactive compressor of a multi-compressor refrigerant system, it is an object of the invention to heat the inactive compressor""s suction and/or discharge line using the heat from an active compressor""s discharge line.
Another object of the invention, in some embodiments, is to provide heat exchange between two refrigerant lines by using the lines themselves to transfer the heat rather than using a dedicated heat exchanger.
Another object of the invention, in some embodiments, is to place two parallel refrigerant lines against each other to provide a line of contact that promotes heat transfer between the two.
Another object of the invention is to insulate two refrigerant lines that are in intimate contact with each other, so that the insulation helps promote more heat transfer between the two lines.
Yet another object of the invention is to ensure that the suction line of the inactive compressor is always heated by the discharge line of the active compressor so that either compressor can be staged.
These and other objects of the invention are provided by a refrigerant system that includes two compressors, each of which have a suction line and a discharge line. To meet lower cooling demands, one compressor is de-activated, while the other continues running. Heat from the discharge line of the running compressor heats the suction or discharge line of the inactive compressor to help prevent refrigerant from condensing in the vicinity of the inactive compressor.
The present invention provides a refrigerant system. The system includes an active compressor having an active discharge line; and an inactive compressor having an inactive suction line and an inactive discharge line. The active discharge line is disposed in heat transfer relationship with at least one of the inactive suction line and the inactive discharge line to help prevent liquid refrigerant from migrating to the inactive compressor.
The present invention also provides a refrigerant system including an active compressor having an active discharge line; and an inactive compressor having an inactive suction line and an inactive discharge line. The active discharge line is held against at least one of the inactive suction line and the inactive discharge line to promote heat transfer from the active discharge line to at least one of the inactive suction line and the inactive discharge line.
The present invention further provides a refrigerant system for meeting a variable cooling demand. The system includes a first compressor, a second compressor, an evaporator, a condenser, a flow restrictor, and a thermal connection. The first compressor is coupled to a first discharge line and a first suction line and is adapted to compress a refrigerant; and the second compressor has an active mode and an inactive mode to provide the refrigerant system with a variable capacity for meeting the variable cooling demand. The second compressor is coupled to a second discharge line and a second suction line. The evaporator has an evaporator inlet and an evaporator outlet with the evaporator inlet being in fluid communication with the first discharge line and the second discharge line. The condenser has a condenser inlet and a condenser outlet with the condenser outlet being in fluid communication with the first suction line and the second suction line. The flow restriction helps place the evaporator outlet in fluid communication with the condenser inlet. The thermal connection places the first discharge line in heat transfer relationship with at least one of the second discharge line and the second suction line. Heat from the first discharge line transfers to at least one of the second discharge line and the second suction line to help prevent liquid refrigerant from migrating to the second compressor when in the inactive mode.